Walter hxesbe



W. KIESER.

DEVICE TO PREVENT SURGING IN CENTRIFUGAL COMPRESSORS.

APPLICATION FILED DEC. 11. 1914.

1,19%,188', Patented Aug. 8, 1916.

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speciflcafioa or letters Patent.

Patented Aug. 8, 191%,

Applioaflon filed December 11, 1914. serial do. 8763M.

To all whom it may concern:

Be it known that 1, WALTER Km, a citizen of the Swiss Republic, residmg at Charlottenburg, Germany, have invented certain new and useful Tm rovemcnts in Devices to Prevent Surg in Centrifugal Compressors, of which the following is a specification.

This invention relates to centrifugal air compressors and its object is to prevent surging of the air column flowing through the machine. This efiect sometimes occurs when the volume of air passing through the compressor and the delivery pipe decreases below a predetermined value and at the same time the pressure exceedsa predetermined amount, as for instance when several air-consumption devices are suddenly shut 0d, and the consequent decrease of load of the compressor causes a rapid increase in its speed. To guard against this diiiiculty, my invention provides a blow-ed valve in the delivery 1pc with means for opening it automatically when the pressure exceeds the safe limit, and with means also for loading the spring of the speed governor of the motor which drives the compressor, so that said motor will not unduly increase its speed.

In the accompanying drawing, Figure 1 is a diagram illustrating the invention, and Fig. 2 1s a section of the slide valve on a larger scale with certain of the parts in a different position from that of Fig. 1.

In the delivery pipe 1 of the compressor 2 is a check valve 3, which closes when a backward surge of air occurs in said pipe. A blow-oli valve having a flanged discharge pipe 4 is connected with the pipe ahead of the check-valve. The double beat valve 5 has a passage through it to a chamber 6 in the valve casing 7. A piston 8 working in a closed cylinder 9 is eosed to the pressure in said chamber, and is secured to the stem 10 of the bloW-ofl valve 5. A spring 11 opposes the pressure on the pimon and normally holds the valve on its seat.

Connected with the pipe 1 beyond the check valve is a casing 12 which is connected by a pipe 131 with the cylinder 9 above the piston 8. In the side of the easing 12 is a vent 14, normally closed by a sllde valve 15, which may be tubular and fitted to slide 'with some friction in the casing 12. A stem 16 passes loosely through an opening 16 in thisvalve leaving an annu'lar space 16 between the stem and the wall of the opening. This is best shown in the enlarged view of Fig. 2. The stem 16 has collars 17 18 above and below it to actuate the slide valve 15 with some lost motion. A differential piston 19, 20 is at tached to the stem 16, one piston working in the upper end of the casing 12 and the other in an enlarged cylinder 21 forming a continuation of said casing. A spring 22 urges said piston downward to keep the vent 14 closed by the valve 15. A station.- ary pin 23 fixed in the perforated cap 24 of the cylinder 21 enters a hole 25 in the piston 20, when the latter moves upward and the piston 19,]eaves the casing 12. The pistons 19, 20 are guided to insure the correct registration of the pin and the hole. A speed governor 26 controls the admission valve 27 of the motor which drives the compressor. The speed governor is loaded by a spring 28 which is attached at one end to a link 29 pivoted to the overnor lever 30. At the other end the spring is connected to the upper end of the stem 10 of the blow-oft valve.

Fig. 1 shows the various parts in their normal positions. The slide valve 15 has been pushed down by collar 17 to a position where the vent 14 is closed. The cylinder 9 above piston 8 is connected to pipe 1 by way of pipe 13 and annular passage 16*, and the piston 19 is located in the upper end of casing 12.

When the pressure in the pipe 1 exceeds the admissible limit, the differential piston in the casing 12 is lifted against the tension of thespring 22 until, just as the collar 18 engages the slide valve 15, the larger piston 20 becomes exposed to the air pressure by the exit of the smaller piston 19 from the casing 12. The valve will, therefore, be quickly, pulled upward, connecting-the vent 14: with the pipe 13 and permitting more or less of the fluid pressure above the piston 8 to escape, the positions which the parts of, the slide valve take being shown in Fig. 2. The air pressure onthe underside of said 1 piston instantly lifts it and opens the blowoff valve 5 to a greater or less extent, thereby relieving the abnormal pressure in the delivery pipe. At the same time, the additional compression of the spring 28 assists the speed governor in closing the admission valve 27 to prevent the driving motor from racin When the piston 20 moves upward, the pin 23 enters the hole 25 and prevents any escape of the air pressure below said.

piston as it moves upward.

When the pressure in the delivery pipe is restored to normal, the differential piston 19, 20 descends, and upon the disengage ment of the piston 20 from the pin 23, the air pressure under the piston will exhaust through the hole 25 and the perforation in the cap 24, so that the spring 22 will uickly move the valve 15 to the position w ere it closes the vent 14. This puts the pipe 1 in connection with the cylinder 9 through the annulan passage 16 and pipe .13, thus balancing the pressures on the opposite sides of the piston 8, so that the spring 11 can close the blow-off valve and' reduce the tension of the spring 28. The load on this spring, there ore, varies correspondingly with the changes of the blow-off valve.

In accordance with the provisions of the patent statutes, I have described the princIple of operation of my invention, to ether with the apparatus which I now consi er to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. The combination with a motor driven centrifugal compressor, having an admission conduit and a discharge conduit, of a blow-off valve in the discharge conduit, means connected with the blow-ofi' valve for opening it upon a predetermined increase in pressure, a regulator for the motor, and means associated therewith and operated upon the opening of the valve for moving the regulator to decrease the speed of the motor.

2. Means to prevent the surging of a motor-driven centrifugal. air com ressor, comprising a blow-off valve in the dblivery pipe, a movable piston controlling said valve, and exposed to the pressure in said pipe, a device 1 onsive to an increase in pressure in said pipe, and means controlled thereby for unbalancing the pressure on said piston.

33. Means for preventing surging in a motor-driven centrifugal air compressor, comprising a blow-off valve in the delivery pipe, a. movable piston controlling said valve and exposed on both sides to the air pressure in said pipe, a vent on the side away from the valve, a valve controlling said vent, and a-differential piston for movin said valve suddenly and exposed on one side to the pressure in pipe.

4. Means for preventing surging in a motor-driven centrifugal air com ressor, comprising a blow-off valve in the elivery pipe, a movable piston controlling said valve and exposed on both sides to the air pressure in said pipe, a vent on the side away from the valve, a valve controlling said vent, a differential piston for moving said valve suddenly and exposed on one slde to the pressure in said pipe, and means for insuring rapid movement of the differential piston in opening the valve and for allowing it to move freely in closing.

5. Means for preventing surging in a motor-driven centrifugal air compressor, comprising a blow-01f valve in the delivery pipe, a movable piston controllin said valve and exposed on both sides to t e air pressure in said ipe, a vent on the side away from the va ve, a valve controlling said vent, a differential piston for moving said valve suddenly and exposed on one side to the I pressure'in said pipe means for insuring rapid movement of the di openin the valve and for allowin it to move reely in closing comprising a ole in the larger piston, and a stationary adapted to fill said hole when the piston moved far enough to permit the air pressure to act u on it. I i

6. Means. or preventing surging in a motor-driven centrifugal air com ressor, comprising a blow-off valve in the olive pipe, a movable piston controlling sai valve and exposed on both sides to the pressure in said pipe, a vent for unbalancing said pressure to open the valve, a pressureresponsive device connected to the pipe and controlling said vent, a speed governor for the motor having aloading spring, and means for increasing the tension of said when the blow-oil valve opens.

spring 7. he combination with a centrifugal compressor having an admission conduit and a discharge conduit, of a non-return valve in the discharge conduit, a blow-off valve in the discharge conduit located in advance of Kitsaid non-return valve as regards the flow of fluid, and a pressure actuated device responsive to the pressure beyond said non return valve for opening the blow-off valve when the pressure reaches a predetermined value.

8. The combination with a centrifugal compressor having an admission conduit and a discharge conduit, of a non-return meenee valve in the discharge conduit, a blow-0E regulator to reduce the speed of the motor valve in the discharge conduit located in when the blow-0E valve is opened l0 advance of said non-return valve as re ards In witness whereof, l[ have hereunto the flow of fluid, a pressure actuated evicemy hand this fifth day of November, 191

5 responsive to the pressure beyond said. non- WALTER return valve for opening the blow-01f valve, Witnesses: a motor for driving the compressor, a regu- WILL? VnfrMANN, lator therefor, and means for actuating the ERNST 

